Merging of distributed datasets

A distributed database, the distributed database comprising:

• multiple nodes for implementing storage and computation for a database management system, the multiple nodes being connected via a network for exchanging data;
• a database management system for managing at least a source dataset and a target dataset, the target dataset being stored in a distributed fashion across the multiple computing nodes, the source dataset comprising multiple source elements, the target dataset comprising multiple target elements;
• a memory having computer readable instructions;
• and
• a plurality of processors located on the multiple nodes for executing the computer readable instructions, the computer readable instructions comprising:
• executing a join command to merge a source dataset with a target dataset, the executing comprising:
• checking for a matching condition between a source element selected from the multiple source elements and one of the multiple target elements;
• calculating a command set of a merge command list, the command list comprising a list of commands to merge the source element with the target element using the matching condition;
• and
• repeatedly executing the command set to merge the source element with the target dataset before checking for the matching condition between a next source element selected from the multiple source elements and one of the multiple target elements,
• wherein the repeated execution of the command set reduces an amount of computing resources required to merge the source dataset with the target dataset, and
• wherein the distributed database is a distributed relational database, the source dataset is a source table, the target dataset is a target table, the multiple source elements are included in multiple source rows, the multiple target elements are included in multiple target rows, the source element is included in a source row, and the command set is included in a command column.

A computer program product for operating a distributed database, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by processors of multiple computing nodes to cause the processors to perform:

• joining a source dataset with a target dataset, the target dataset being stored in a distributed fashion across the multiple computing nodes, the source dataset comprising multiple source elements, the target dataset comprising multiple target elements, the joining comprising:
• checking for a matching condition between a source element selected from the multiple source elements and one of the multiple target elements;
• calculating a command set of a merge command list, the command set comprising a list of commands to merge the source element with the target element using the matching condition;
• and
• executing the command set to merge the source element with the target dataset before checking for the matching condition between a next source element selected from the multiple source elements and one of the multiple target elements,
• wherein the repeated execution of the command set reduces an amount of computing resources required to merge the source dataset with the target dataset, and
• wherein the distributed database is a distributed relational database, the source dataset is a source table, the target dataset is a target table, the multiple source elements are included in multiple source rows, the multiple target elements are included in multiple target rows, the source element is included in a source row, and the command set is included in a command column.